using your new rule for Q and S ....
Q(a,b) S(a+2, b+5)
select any values you want for a and b; say a=6 and b=-1 .... random picks
Q(6,-1) S(6+2, -1+5)
Q(6,-1) S(8, 4)
now that I have a set of points that matches the rule, lets determine its own midpoint as is
(7 , 3/2)
now i want this midpoint to be at (0,-3/2), so lets see how we adjust it to get there
(7 , 3/2)
-7, -6/2 <---- i need to move Q and S by the same
--------
(0, -3/2)
since we have to move the midpoint by (-7,-3), we will have to move Q and S by the same amount
Q(6,-1) S(8, 4)
-7 -3 -7 -3
------- --------
Q(-1,-4) S(1, 1)
now we have a set of points Q and S that match the given rule; and is located in the proper spot